Systems and methods for dynamic additive manufacturing welding program planning

Additive manufacturing is a process that deposits material in a layered fashion to build up a part into a particular geometry. Various techniques have been implemented to build with specific materials. However, maintaining desired adhesion between layers, and/or integrity of the part has proven challenging with some materials.

The present disclosure relates generally to additive manufacturing systems, and more particularly to an additive manufacturing tool to build up a part by employing welding-type programs. In some examples, control circuitry controls the additive manufacturing tool to operate in a first welding-type program of a plurality of welding-type programs in response to a determination that the measured temperature is below a first threshold temperature of one or more threshold temperatures, and control the additive manufacturing tool to operate in a second welding-type program of the plurality of welding-type programs in response to a determination that the measured temperature is above the first threshold temperature, substantially as illustrated by and described in connection with at least one of the figures, as set forth more completely in the claims.

The figures are not necessarily to scale. Where appropriate, similar or identical reference numbers are used to refer to similar or identical components.

The present disclosure describes systems and methods for forming a multilayered part by additive manufacturing techniques. An additive manufacturing system employs sensor data (e.g., from a temperature sensor) in conjunction with a plurality of welding-type programs and stored geometric models to build up the part by application of material (e.g., an electrode wire) into a series of layers.

The present disclosure relates generally to additive manufacturing systems, and more particularly to an additive manufacturing tool to build up a part by transitioning between welding-type programs. The system is designed to adjust the heat input by changing the welding-type program before and/or during operation to build the part. For example, one or more temperature sensors can be placed along the weld path (e.g., in front of the additive manufacturing tool or welding torch) to measure the temperature at one or more locations (e.g., as the weld bead forms). If a relatively high temperature is measured (in comparison to one or more threshold temperatures), then the control circuitry will command a change in the welding-type program to a welding-type program that has a lower heat output (e.g., Control Short Circuiting (CSC) welding-type program, a Joule heating welding-type program). If a relatively low temperature is measured, then the control circuitry will command a change to a welding-type program that has a higher heat output (e.g., Constant Voltage (CV) spray welding-type program, a pulsed spray welding-type program, etc.).

In this manner, the additive manufacturing system controls the heat of the application to regulate temperature of the part during fabrication. The result is greater a part, such as a multilayer part, with enhanced adhesion and limited amount of warp between layers.

Additive manufacturing is any of various processes in which material is joined or solidified under computer control to create a three-dimensional object, with material being added together in a layered fashion. For example, three-dimensional (3D) printing is used in both rapid prototyping and additive manufacturing using technologies such as stereolithography (SLA) or fused deposit modeling (FDM).

Through additive manufacturing techniques, objects of almost any shape or geometry can be created, typically by use of a digital three-dimensional model. Traditional techniques for creating an object like injection molding can be less expensive for the manufacture of some products in high quantities. By contrast, additive manufacturing may be faster, more flexible and/or less expensive when producing fewer parts. Thus, additive manufacturing systems give designers and manufacturers the ability to produce parts and concept models in less time with greater flexibility. Thus, unlike material removed from a stock in conventional machining processes, additive manufacturing builds a three-dimensional object from a computer-aided design (CAD) model or Additive Manufacturing File Format (AMF) file, usually by successively adding material (e.g., an electrode wire) layer by layer.

Powder is a widely used deposition material because powder provides a flexible and robust process. However, powder based processes have been developed towards the manufacture of small and complex geometries. Using wire as a deposition material is a less common but useful technique. Wire deposition material is especially useful in the manufacturing of large and sturdy structures. Compared to powder, wire deposition has several advantages, including near 100% utilization of material, good out-of-position tolerance, better surface finish, high deposition rate, cleaner work environment, and lower cost of materials.

In some examples, the additive manufacturing system is configured to build the part by direct energy deposition (DED) techniques. For instance, a multilayer part can be fabricated layer by layer through introducing material (e.g., a consumable electrode wire) via one or more of a variety of welding technologies (e.g., Metal Inert Gas (MIG) welding, plasma welding, laser hot-wire DED, etc.). Within MIG welding processes, different welding programs can be implemented, some with different heat profiles. For example, a pulse welding-type program is associated with a high heat profile relative to a hot wire welding-type program.

In the DED process, the feedstock material, which comes in either metal powder or wire form, is pushed through a feed nozzle where it is melted by a focused heat source (e.g., a welding arc) and successively added to build the layers of the part. Material is added layer by layer and solidifies as it cools, creating new features on the underlying layers of the part. Some of the advantages of employing this process include a wide range of metals that can be used, such as titanium, stainless steel, aluminum, nickel, copper, alloys, and any number of other specialty materials and/or composite material. By these processes, relatively large parts can be built at a relatively fast pace (in comparison to other additive manufacturing techniques), with relatively little wasted material.

However, materials such as metal are heated and cooled at a rapid rate when building a part using arc welding processes. For example, at the start of a DED process, the substrate upon which the part is being formed is relatively cold. Thus, heat from a welding process is absorbed and dissipates quickly, which causes a lack of fusion at the first few layers (see, e.g.,).

After several layers have been formed, the substrate temperature has increased, and heat from the molten pool dissipates through the built up layers toward the substrate. As this continues, the heat accumulates and the cooling rate slows, resulting in a hotter and bigger molten pool. Eventually, the molten pool will collapse, causing damage to the part and halting the DED process (see, e.g.,).

In an effort to control the heat input to the molten pool, size and temperature may be regulated. For example, if the molten pool size or temperature exceeds a certain value, a variable of the process (e.g., welding speed, wire feed speed) can be adjusted resulting in a reduced heat input. However, in a MIG welding program, wire feed speed and heat input are controlled as a single factor. Therefore, adjustment of these variables leads to a relatively small change to the heat input, which may not effectively address the thermal accumulation issue.

Another option is through adjusting the multilayered part path planning, which may provide the underlying layer more time to cool down. However, adjusting the layered path plan to address heat requires complex path planning work and intense customization. Moreover, alternating or modifying the path plan can significantly slow down the fabrication process, as the process must stop, adjust position, and start frequently.

Yet another option is to preheat the substrate to a suitably high temperature, which encourages fusion with the material deposited during the first few passes while using a low heat input process (e.g., hot wire or CSC welding-type programs). However, preheating requires an additional step and time in the part build cycle, by heating up the substrate first before printing, often with a dedicated heating system, which adds further complexity. For example, to preheat a substrate, a system should include an integrated heater or require an oven or furnace, which would require transportation and handling the substrate in order to print the desired parts.

By use of the additive manufacturing system disclosed herein, the temperature and weld bead characteristics can be regulated to improve layer fusion and consistency. Employing a temperature sensor to monitor the temperature of the substrate (including each previous layer, which serves as a substrate for a successive layer), allows the control circuitry to determine a suitable welding-type program for a measured temperature during part buildup to ensure suitable fusion between layers and material wetting to the substrate at the beginning of the additive manufacturing process.

Advantageously, heat input is regulated via the control circuitry, thereby limiting the use of additional and complex components.

Accordingly, the additive manufacturing system implements changes to the welding-type process from within the power source, without the use of preheating devices (e.g., laser systems, substrate heating systems, wire electrode heating systems, etc.), or altering the part planning (e.g., to reduce overheating). These advantages are realized by use of control circuitry to dynamically adjust operation of the welding-type program in response to a measured temperature or heat profile associated with the part being formed and/or the welding output.

For example, at the beginning of an additive manufacturing operation, a high heat output process (e.g., a spray welding-type program) may be selected to quickly heat a cold substrate and encourage fusion on the first few layers of the part. The substrate (and part) may heat quickly, such that a measured temperature may exceed a first threshold temperature value. In response, and to avoid an overheated weld bead, the control circuitry can switch to a welding-type program with a relatively low heat profile (e.g., a short circuiting welding-type program, a joule heating welding-type program, etc.). The system is configured to monitor heat and transition between welding-type programs dynamically before and/or during an additive manufacturing operation.

Additionally or alternatively, various welding parameters may be dynamically adjusted to modify the heat profile beyond welding-type program. For instance, with a short circuiting process, the wire feeding speed may be capped at certain wire feeding speed, which is lower than the setting wire feeding speed of high heat input program. If so, in order to match the bead size, once switching to the low heat input process, the welding speed can be slowed down proportionally. Similarly, at a higher heat output welding-type program (e.g., CV spray, pulse spray, etc.), one or more of the wire feed speed, travel speed, and/or deposition rate can be relatively higher.

In some examples, the control circuitry determines that the temperature and/or a change in temperature is great enough that one or more intermediate welding-type programs are skipped over to implement the desired program. For example, if deposition along the path plan brings the additive manufacturing tool from a heated portion of the part to an unheated portion, the measured temperature (or change in temperature) may require a transition from a low heat “hot wire” welding-type program to a high heat spray welding-type program, thereby bypassing one or more intermediate welding-type programs.

Advantageously, the disclosed additive manufacturing systems and methods achieve improved fusion, wetting, speed and flexibility without the need for additional and complex components. For instance, conventional systems use ovens and/or other heating systems for substrate preheating. Some conventional systems require an additional laser system to provide heat, adding complexity and expense. Further, complex path planning and/or systems to carry it out are avoided, with the added speed associated with a dynamic system, as disclosed herein (e.g., by eliminating the need to move around the part platform or wait for an overheated part to cool).

In disclosed examples, an additive manufacturing system includes an additive manufacturing tool configured to advance an electrode wire to a weld puddle on a surface of a part, a sensor to measure a temperature of the part and control circuitry. The control circuitry is configured to monitor the measured temperature associated with the part; compare the measured temperature to one or more threshold temperatures; control the additive manufacturing tool to operate in a first welding-type program of a plurality of welding-type programs in response to a determination that the measured temperature is below a first threshold temperature of the one or more threshold temperatures, and control the additive manufacturing tool to operate in a second welding-type program of the plurality of welding-type programs in response to a determination that the measured temperature is above the first threshold temperature.

In some examples, the first welding-type program comprises a spray welding-type program. In examples, the spray welding-type program comprises a Constant Voltage (CV) spray welding-type program or a pulsed spray welding-type program. In examples, the second welding-type program comprises a Control Short Circuit (CSC) welding-type program.

In some examples, the control circuitry is further configured to control the additive manufacturing tool to operate in a third welding-type program in response to a determination that the measured temperature is above a second threshold temperature of the one or more threshold temperatures. In examples, the third welding-type program comprises a joule heating welding-type program. In examples, the additive manufacturing tool comprises a metal inert gas (MIG) arc welding torch.

In some examples, the part is a multi-layer part being formed by the additive manufacturing system. In examples, the control circuitry is further configured to receive one or more three-dimensional models of the multi-layer part; and adjust an operational characteristic of the system based on one or more of the three-dimensional models. In examples, the operational characteristic comprises a wire feeder direction of the wire feeder motor, a power output, a deposition path, a deposition sequence, or a tool angle, based on one or more of the three-dimensional models.

In disclosed examples, an additive manufacturing system includes an additive manufacturing tool configured to advance an electrode wire to a weld puddle on a surface of a part, a sensor to measure a temperature of the part and control circuitry. The control circuitry is configured to monitor the measured temperature associated with the part, compare the measured temperature to a list of temperatures associated with a plurality of welding-type programs, determine whether the measured temperature corresponds to a first welding-type program or a second welding-type program of the plurality of welding-type programs based on the comparison, control one or more of a wire feed speed or a travel speed of the additive manufacturing tool to operate at a first wire feed speed or a first travel speed corresponding to the first welding-type program based on the determination that the temperature corresponds to the first welding-type program, and control one or more of the wire feed speed or the travel speed of the additive manufacturing tool to operate at a second wire feed speed or a second travel speed corresponding to the second welding-type program based on the determination that the temperature corresponds to the second welding-type program.

In some examples, the control circuitry is further configured to compare the temperature measurements over a period of time, calculate a rate of temperature change of over the period, compare the rate of temperature change to a list of threshold rate of temperature change values, control the additive manufacturing tool to operate in the first welding-type program based at least in part on a determination that the rate of temperature change is below a first temperature change value, and control the additive manufacturing tool to operate in a second welding-type program based at least in part on a determination that the rate of temperature change is above the first temperature change value.

In some examples, a camera is used to capture one or more weld bead characteristics. The control circuitry is further configured to calculate weld bead size based on the one or more weld bead characteristics, compare the weld bead size to a list of threshold weld bead size values, control the additive manufacturing tool to operate in the first welding-type program based at least in part on a determination that the weld bead size is below a first weld bead size value, and control the additive manufacturing tool to operate in a second welding-type program based at least in part on a determination that the weld bead size is above the first weld bead size value.

In examples, the control circuitry is further configured to control one or more of the wire feed speed or the travel speed of the additive manufacturing tool to operate at the first wire feed speed or the first travel speed based in part on the first weld bead size value, and control one or more of the wire feed speed or the travel speed of the additive manufacturing tool to operate at the second wire feed speed or the second travel speed based in part on the second weld bead size value.

In some examples, the control circuitry is further configured to monitor a current or a voltage associated with a power output to the additive manufacturing tool, compare the current or voltage to a list of current or voltage values, control the additive manufacturing tool to operate in the first welding-type program based at least in part on a determination that the current or voltage is below a first current or voltage value, and control the additive manufacturing tool to operate in a second welding-type program based at least in part on a determination that the current or voltage is above the first current or voltage value.

In examples, the additive manufacturing tool comprises an arc welding-type torch. In examples, the one or more temperatures correspond to one or more threshold temperatures.

In some examples, the part is a multi-layer part being formed by the additive manufacturing system. In examples, the control circuitry is further configured to receive one or more three-dimensional models of the multi-layer part, and adjust the wire feed speed or the travel speed of the additive manufacturing tool based on one or more of the three-dimensional models. In examples, the control circuitry is further configured to adjust an operational characteristic of the system based on one or more of the three-dimensional models.

As used herein, the term “additive manufacturing”, is a manufacturing process in which material is joined or solidified under computer control to create a three-dimensional object, with material being added together in a layered fashion.

As used herein, the term “direct energy deposition” or DED, is a manufacturing process in which material is added together in a layered fashion, by use of one or more material forming technologies.

As used herein, the term “welding-type power” refers to power suitable for welding, plasma cutting, induction heating, CAC-A and/or hot wire welding/preheating (including laser welding and laser cladding). As used herein, the term “welding-type power supply” and/or “power supply” refers to any device capable of, when power is applied thereto, supplying welding, plasma cutting, induction heating, CAC-A and/or hot wire welding/preheating (including laser welding and laser cladding) power, including but not limited to inverters, converters, resonant power supplies, quasi-resonant power supplies, and the like, as well as control circuitry and other ancillary circuitry associated therewith.

As used herein, a “circuit” or “circuitry” includes any analog and/or digital components, power and/or control elements, such as a microprocessor, digital signal processor (DSP), software, and the like, discrete and/or integrated components, or portions and/or combinations thereof.

As used herein, the term “pulsed welding” or “pulsed MIG welding” refers to techniques in which a pulsed power waveform is generated, such as to control deposition of droplets of metal into the progressing weld puddle.

As used herein, the term “boost converter” is a converter used in a circuit that boosts a voltage. For example, a boost converter can be a type of step-up converter, such as a DC-to-DC power converter that steps up voltage while stepping down current from its input (e.g., from the starter battery) to its output (e.g., a load and/or attached power bus). It is a type of switched-mode power supply.

As used herein, the term “buck converter” (e.g., a step-down converter) refers to a power converter that steps down voltage (e.g., while stepping up current) from its input to its output.

As used, herein, the term “memory” and/or “memory device” means computer hardware or circuitry to store information for use by a processor and/or other digital device. The memory and/or memory device can be any suitable type of computer memory or any other type of electronic storage medium, such as, for example, read-only memory (ROM), random access memory (RAM), cache memory, compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically-erasable programmable read-only memory (EEPROM), flash memory, solid-state storage, a computer-readable medium, or the like.

As used herein, the term “torch,” “tool” or “welding-type tool” can include a hand-held or robotic welding torch, gun, or other device used to create the welding arc.

As used herein, the term “hot wire” refers to a welding-type program such that an electrode wire being consumed during operation is electrified to heat the wire without creating a welding arc.

illustrates an example additive manufacturing system. As shown, the additive manufacturing ofis an arc welding system, although other additive manufacturing processes and techniques are considered. A power supplyand a wire feederare coupled via conductors or conduits. In the illustrated example, the power supplyis separate from the wire feeder, such that the wire feeder may be positioned at some distance from the power supply near a welding location. However, in some examples, the wire feeder may be integrated with the power supply. In such cases, the conduitswould be internal to the system. In examples in which the wire feederis separate from the power supply, terminals are typically provided on the power supplyand on the wire feederto allow the conductors or conduits to be coupled to the systems so as to allow for power and gas to be provided to the wire feederfrom the power supply, and to allow data to be exchanged between the two devices.

The system is configured to provide wire, power, and shielding gas to an additive manufacturing tool or welding torch. The toolmay be of many different types, and may allow for the feed of a welding wireand gas to a location adjacent to a substrate or platformupon which a partis to be formed. In some examples, a second conductormay be run to the welding substrateso as to complete an electrical circuit between the power supply and the workpiece.

The welding system is configured for data settings to be selected by the operator and/or a welding sequence, such as via an operator interfaceprovided on the power supplyor via interfaceto a remote computer or processor. The operator interfacemay be incorporated into a front faceplate of the power supply, and may allow for selection of settings such as the welding process, the type of wire to be used, voltage and current settings, and so forth. In particular, the system is configured to allow for welding with various materials, including steels, aluminums, alloys, and/or other welding wire that is channeled through the tool. Further, the system is configured to employ welding wires with a variety of cross-sectional geometries (e.g., circular, substantially flat, triangular, etc.). These weld settings are communicated to a control circuitry (or control circuit)within the power supply. The system may be particularly adapted to implement welding regimes configured for certain welding wire types.

Additionally or alternatively, process instructions for additive manufacturing can be provided via a weld sequence program, such as stored on a memory accessible to a processor/control circuitryassociated with the power supply. In such a case, the sequencer can employ stored information (e.g., associated with a desired product configuration and/or process, including historical data), and/or customizable by a user. For instance, information associated with a particular design (e.g., one or more three-dimensional models and/or thermal profiles associated with the part, material characteristics, system control parameters, etc.) corresponding to the partcan be stored in a memory and/or provided via a network interface, as described in greater detail with respect to. Thus, the information can be used to control operation of the system to facilitate formation of the part, such as by controlling a power output from the power supply, wire feeder motors,, robotic system, an optional laser system, etc.

In this manner, the system and/or the control circuitrycontrols formation of the partby transitioning between welding-type programs associated with one or more temperatures or heat profiles during the additive manufacturing process. For example, a sensor(s)can measure operational parameters associated with operation of the system (e.g., heat, current, voltage, inductance, phase, power, speed, acceleration, orientation, position, etc.). The sensed operational characteristic (e.g., voltage, current, orientation, temperature, shape, speed, etc.) can be provided to the control circuitryor other controller (e.g., control circuitry, a controller associated with the robotic system, etc.) to further control the additive manufacturing process. In examples, a sensorincludes a heat sensor (e.g., an infrared (IR) camera, a thermistor, a thermometer, etc.)

In this manner, the system and/or the control circuitrycontrols formation of the partby adjusting one or more operational characteristics of the system during the additive manufacturing process. The operational characteristics may include, but are not limited to, wire feeder speed, wire feeder direction, travel speed, power output, process mode, deposition path, deposition sequence, torch angle, torch height, etc.